The present invention relates to a transfer device associated with a power transmission unit for an automotive vehicle of four wheel drive type, and more particularly to a tansfer device of the type which includes an input shaft for connection to an output shaft of the transmission unit, a first output shaft axially aligned with the input shaft through an intermediate shaft, a second output shaft located parallely apart from the input and intermediate shafts, a selector gear unit for selectively completing low and high speed gear trains among the input shaft and the first and second output shafts, and a differential gear unit mounted on the intermediate shaft to distribute drive power to the first and second output shafts at a predetermined gear ratio.
In a conventional transfer device of this kind, for example, as shown in FIG. 8, an input shaft 1 is axially aligned with a first output shaft 3a through an intermediate shaft 2, and a second output shaft 5 is located parallely apart from the input and intermediate shafts. In the transfer device, a first selector gear unit 6 is associated with a change-speed gearing 4 to selectively complete low and high speed gear trains, and a differential gear unit 3 includes an input member connected with the intermediate shaft 2 and a pair of output members in the form of side gears 3c, 3b. Power transmission from the side gear 3c to the second output shaft 5 is conducted by a chain drive mechanism 8 which is arranged between the change-speed gearing 4 and the differential gear unit 3. The chain drive mechanism 8 comprises a pair of sprockets 8a, 8b respectively connected with the side gear 3c and the second output shaft 5 and a drive chain 8c stretched over the sprockets 8a, 8b. The transfer device further includes a second selector gear unit 7 which is assembled between the chain drive mechanism 8 and the differential gear unit 3 to control the operation of differential gear unit 3.
In such a transfer device as described above, the chain drive mechanism 8 enlarges the size of the transfer device and increases the number of component parts of the transfer device. Additionally, the first and second selector gear units 6 and 7 are independently operated by separate shift mechanisms which are complicated in construction and occupy a large space within the transfer device.